Black is in time with this thematic knight maneuver.
13. f2f4  13... h7h6 A new move. 13...Nc5 and 13...0-0 were tested in correspondence games. 14. e1g1 A surprising move. One would imagine that White should castle queenside, especially after the opening of the h-file. 14... h6g5  15. h4g5 